1. Field of the Invention
The invention relates to a method of registering a model image serving as a reference image for image inspection, and an apparatus therefor.
2. Description of the Related Art
In a device designed to sequentially inspect the same kind of objects by means of image processing, such as an image processor for inspecting a product carried on a conveyor, an inspection is carried out in the following way. A model image serving as a reference image during image inspection is registered in advance; such a part of a target image taken by the camera as corresponding to the model image is extracted; and the extracted image is compared with the model image.
Some conventional model image registration methods carried out by the image processor for image inspection are characterized as follows.
(1) A model image is registered by manually positioning a target model, a camera, or the like so that the model image becomes as horizontal or vertical as possible on a display screen of a monitor.
(2) A model image is registered (or re-registered) by stopping a target model if the target model is moving along a line such as a conveyor.
(3) A model image is registered part by part while consecutively rotating a target model manually if the target model is not arranged substantially horizontally, but arranged substantially concentric.
However, the aforementioned methods address the following shortcomings.
With respect to case (1), since the target model, the camera, or the like have to be positioned manually so that the model image becomes substantially horizontal or vertical, the positioning operation not only is cumbersome but also entails skill.
With respect to case (2), since the line have to be stopped at the time the model image is registered (re-registered), the problem of reducing productivity arises. In addition, the operation of stopping and resuming the line have to be additionally performed.
With respect to case (3), the positioning operation that entails more time than in the case (1) is required.